The research being carried out under this project is generally concerned with the effects of total parenteral nutrition (TPN) on somatic as well as organ growth in the newborn puppy. As a preliminary step, normative studies are conducted on the growth rate, body composition, and biochemical growth of selected areas of the CNS (i.e., DNA, RNA, protein and key classes of brain lipids) and other organs of normal beagle puppies from birth to 42 days of life. With this background, the effects of TPN on the above variables will be studied. We have perfected a technique for inserting and maintaining central venous feeding catheters in newborn beagle dogs. Such animals can be successfully fed completely by the parenteral route for up to 42 days of life. The first series of experiments will involve the study of the effects of conventional fat-free TPN infusates on body growth and chemical growth of selected organs compared to controls and to semistarved animals. In a subsequent group, the effects of fat-containing TPN infusates on the same variables will be pursued.